Small boats are widely used for recreational applications including water sports, hunting and fishing, and for various working uses around lakes, farm ponds, harbors and shipyards. When such boats are to be transported from place to place, they must typically be mounted on a trailer which is towed to the destination and used to launch the boat from a ramp. However, it is often desirable to transport such small boats without having to mount them on a separate trailer. One solution to this challenge is Applicant's U.S. Pat. No. 3,933,112, which provided a system for carrying a small boat atop a car or van, in which the inverted boat served as a temporary roof for a van. Hoist systems are available for raising such boats into position on the van roof or lowering them for launch. Another approach, ca. 1990, was the "CAP-A-BOAT," manufactured by ALTEC ENGINEERING of Elkhart, Ind. A pickup truck with a conventional "cap" covering the bed carried a flat-bottomed fishing boat in inverted position atop the cap. An electrical lift was provided for launching and retrieving the boat.
Small trucks of various types have become very popular, and include some of the largest selling motor vehicles in the United States, particularly in the form of pickup trucks ranging from "mini"-pickups through the modified passenger chassis truck (e.g., the Chevrolet "El Camino") to the standard two-door and four-door pickups and even larger pickups with long beds and reinforced rear wheels and axles. See, e.g., "Pickups: From the Barn to the Carport," New York Times, Jul. 18, 1993, p. F-8. Many of these pickup trucks are adapted to have camper units mounted in the beds, or to have the beds at least temporarily covered with a rigid structure or covering which may be called a "cap". Since such trucks are widely used in recreation and work applications where it would be desirable to transport a boat, it would be useful to produce a suitable boat which is adapted for transport by such trucks without the need of a trailer.
Efforts along these lines found in the prior art include U.S. Pat. No. 3,508,787, which discloses enclosures for pickup truck beds which are convertible into small boats. The enclosure, best seen in FIGS. 9 to 12 of the patent, forms a portion of the inverted hull of a conventional boat when in position on the truck. U.S. Pat. No. 4,236,474 discloses boats which include hull bodies designed to be be carried in inverted position in the bed of a vehicle such as a pickup truck. The hull body is assembled into a boat by adding at least one hull extension. As shown in FIGS. 16 and 17, such hull extensions can form the twin hulls of a catamaran. U.S. Pat. No. 4,624,209 discloses a "readily portable kit for assembling a multiple-hulled watercraft, such as a catamaran, from two or more open-hulled boats such as canoes". As shown in FIGS. 1 and 2, the disassembled kit can be mounted for transport atop a van.
A modern design for ships and boats known as the Small Waterplane Area Twin Hull (SWATH) design has been used in a variety of contexts ranging from small unmanned craft to large ships. Large passenger cruise liners and ferries using this design are in operation, and it has been proposed to use it for a cruise liner as the largest SWATH vessel ever built, the Radisson Diamond. SWATH ship and boat designs offer many advantages including speed and stability--see, e.g., "Help for the Queasy: Odd Ship Smooths Sea's Ups and Downs", The Wall Street Journal, Nov. 20, 1987, page 31. The U.S. Navy has used such designs for a variety of ships, and has patented many of the design concepts--see Applicant's article, "New Shape in Ships," U.S. Naval Institute Proceedings February, 1985, pp. 38-47.
Applicant's U.S. Pat. No. 4,553,037 also discloses a number of useful applications of SWATH hulls. Those depicted in FIGS. 3, 4 and 5 are of interest for the present application. A particularly useful feature for SWATH vessels disclosed in this patent (at column 6 and FIG. 14) is the concept of "angled struts" which improve the stability of the vessel in rough water. This patent is incorporated herein by reference for its descriptions and drawings of SWATH hulls and design principles. See also the paper presented by Applicant et al., "Innovative Uses of a Modified SWATH For Ocean Engineering," OCEANS Conference sponsored by Marine Technology and IEEE Ocean Engineering Society, Washington, D.C., Sep. 10-12, 1984 (PROCEEDINGS OF OCEANS, pp. 768-772).
General characteristics of SWATH vessels, with particular reference to naval ships and craft, are described by Gore in "SWATH SHIPS," Chapt. 3 of "Modern Ships and Craft", Naval Engineers Journal, February 1985, pp. 83-112.
Catamarans are among the oldest of boat designs, having been used by ocean-going Polynesians, and are widely used to this day as recreational sail and power boats. Due to their wide beam, transport on motor vehicles or trailers has often required at least partial disassembly, as described above in U.S. Pat. No. 4,624,209. Representative small catamaran boats are disclosed in U.S. Pat. Nos. 4,813,366; 4,086,863; Des. 184,184 and Des. 278,138.
In boats of the size range contemplated for the present invention, SWATH boats have clear advantages of reduced motions in a seaway over catamarans. Furthermore, due to the generally shallow, broad hulls typically employed in catamarans, one would not expect to find a catamaran of a length and beam suitable for enclosing the bed of a pickup truck or the like which included hulls deep (or tall) enough to provide a cap or closure of a suitable height when the boat was positioned on the sidewalls of the bed in the upright position.